"We need to know what he's actually returned as a tax return, we need to know why he put this money overseas in the first place and whether he made anything out of it or not before 2010 when he became Prime Minister."

Jeremy Corbyn said: "I want to see the papers" (Photo: BBC)

Shadow Chancellor John McDonnell backed to call to know if the PM was being honest, telling BBC Radio 5 Live: "We haven't seen the full tax returns yet so we can't make that judgement. What we've seen is a summary".

As the clamour grew today for full transparency, Mr Corbyn called for a sleaze watchdog to probe whether the PM's shares in his dad's offshore fund should have been formally declared.

David and Samantha Cameron trousered £19,000 profit by selling shares in Bahamas-based Blairmore Holdings - but did not declare it on the MPs' register of interests.

That's because MPs are only required to register shares with a value of more than £70,000.

Labour's John McDonnell suggested even councillors could publish their affairs